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Multiple Choice
If 100.0 mL of 0.100 M Na2SO4 is added to 200.0 mL of 0.150 M NaCl, what is the concentration of Na+ ions in the final solution? Assume that the volumes are additive.
A
0.200 M
B
0.250 M
C
0.150 M
D
0.100 M
Verified step by step guidance
1
Calculate the moles of Na+ ions contributed by Na2SO4. Since Na2SO4 dissociates into 2 Na+ ions and 1 SO4^2- ion, use the formula: \( \text{moles of Na+ from Na2SO4} = 2 \times \text{volume (L)} \times \text{molarity (M)} \).
Calculate the moles of Na+ ions contributed by NaCl. NaCl dissociates into 1 Na+ ion and 1 Cl^- ion, so use the formula: \( \text{moles of Na+ from NaCl} = \text{volume (L)} \times \text{molarity (M)} \).
Add the moles of Na+ ions from both Na2SO4 and NaCl to find the total moles of Na+ ions in the solution.
Calculate the total volume of the solution by adding the volumes of the two solutions: \( \text{total volume} = \text{volume of Na2SO4} + \text{volume of NaCl} \).
Determine the concentration of Na+ ions in the final solution using the formula: \( \text{concentration of Na+} = \frac{\text{total moles of Na+}}{\text{total volume (L)}} \).